What are some of the clues for noticing the difference between a legit product a fake one?

Just as the title states, i was cautioned against buying carelessly some time ago when i almost wasted money on a bootleg...but honestly, i don't really know what to signs to look for when looking up animes online, especially on eBay, so some information, pointers, help, etc would be much appreciated :)

the other thing I noticed is a lot of bootlegs have either a very high number of episodes per dvd than you would expect, and tend to also have chinese subtitles, along with english subtitles. As you probably noticed, that particular dvd set has 25 episodes spanning across 2 dvds. That's about 12ish episodes each dvd, even if it was a dual layer dvd (highly unlikely) it would still suffer from a great deal of compression.

Just as the title states, i was cautioned against buying carelessly some time ago when i almost wasted money on a bootleg...but honestly, i don't really know what to signs to look for when looking up animes online, especially on eBay, so some information, pointers, help, etc would be much appreciated :)

That Gosick DVD set is a bootleg. LF is a known Malaysian bootlegging company. Malaysia and China are notorious for selling bootlegged anime DVD sets and should generally be avoided when buying on ebay. Other obvious bootleg tip-offs are an unusually high number of episodes across a small number of DVDs, a ridiculously low price, Malaysian or Chinese subtitles, and Region-0 (i.e. region free) encoding, all of which are things publishers almost never do. Another good way to spot a bootleg is to check the publishing company on the DVD box label and research them on the net to see if they're among lists of known bootleggers. These tips also apply to Amazon.com, which surprisingly also lists a number of bootleg anime DVDs.

If you're simply looking for a legitimate Region 1 release of an anime series, the easiest way I know of to check if one exists would be to go to Anime News Network's encyclopedia, which usually has images of DVD covers for all the known R1 DVD releases for a series (just select a series and scroll down to the DVD section for links to the title's various DVD releases).

As for Gosick, if you check its Wikipedia article it seems that Bandai had announced in 2011 an R1 release for the series, but unfortunately stepped out of the R1 anime market in early 2012, which means there's not yet a legitimate R1 release for the series. That said, according to the ANN encyclopedia entry for Gosick it does appear that the series got a legitimate subtitled release in Australia from Madman Entertainment. A quick check on ebay turns up some copies of the legitimate Australian DVD sets (set 1 and set 2), albeit they're fairly expensive. Australian DVDs are Region 4, so you'd have to get a region-free DVD player in order to watch them.

This can be put up for discussion, just like how to look at counterfiet toys and such. Although, it goes to a more personal question, so there's that too. Well, let's see.

Yeah, it's definitely something that can make a good discussion topic (in which some advice may also be offered), but the OP seemed to be asking for some specific advice. I guess if enough of us use this thread as a discussion launcher, we could keep it. The mods may decide.

In the case of Amazon, it would only apply to marketplace sellers, not from products sold directly from Amazon, although fulfilled by Amazon is different than sold by Amazon.

Another giveaway in the ebay link is also in the pictures of the back of the box, the Chinese language description, and the Chinese title above the original title on the cover. That wouldn't be on a legitimate US or Japanese version.